It is known to create on an identity document an image by producing two or more images of an object from different angles. By providing in the image such two images, a viewer of the image perceives a stereo image of the object shown.
An identity document of this type is disclosed in WO 2006/110038 (A2) wherein an authentication mark comprising two or three images that are engraved by laser light through a lens structure in a sensitive layer. By tilting the identity document at a different angle, one of the images can always be seen. The angle at which the different images are applied is −27°, 0° and +27° respectively. This provides added security for an identity document such as a passport, driving license and the like. However, for the user, i.e. the person checking the identification document, it is not always clear that such different images are present. Moreover, at certain checkpoints there is little time to check all the authentication marks in an identity document, as a result of which checking for the presence of the different images is overlooked. Consequently, the authentication marks are not always optimally used under normal circumstances.
An further identity document disclosed in applicant's WO 2011/122943 (A1) describing how an image with two rotated images can be obtained from a photo image by means of projection in an image processing device with the aid of special software. The rotation images are being applied in an interlaced manner under linear lenses in order to form a stereoscopic portrait image for use in a security or identification document.
A disadvantage of the known structure is that the stereographic perception may be adversely effected through calculation of the rotated images, and that images calculated in this way are thereby less suitable for use in security and identification documents such as passports, driving licenses, access badges, etc. Therefore, the authenticity of a three-dimensional image of this type is difficult to establish on visual inspection.
It is an object of this invention to provide an identity document, from which the photo can be easily authenticated. Accordingly it would be desirable to overcome or ameliorate at least one of the disadvantages of the prior art.